Inconsistent data, such as duplicate data or out-of-order data, can arise from various operating conditions, including data re-transmission resulting from previous error recovery actions, as well as from other conditions. The integrity of this type of data is suspect, and thus, problematic.
Certain communications protocols are configured with an assumption that the data cannot be duplicated or be out-of-order. Examples of these protocols include Intersystem Channel (ISC), ESCON® and FICON® protocols offered by International Business Machines Corporation. Violation of this assumption may cause catastrophic failures, affecting operation of the entire system.
Although these protocols assume the data cannot be duplicated or out-of-order, this may not be necessarily true when these protocols are used in communications networks that also include other protocols. For example, to transport data over longer distances, ISC or other protocols may be used in conjunction with a Synchronous Optical Network (SONET) or Internet Protocol (IP) network to transport the data. When combining the different protocols, the data on the ISC links may become inconsistent.